Initiation Site Research Articles

Oncogene activated human breast luminal progenitors contribute basally located myoepithelial cells

BackgroundBasal-like breast cancer originates in luminal progenitors, frequently with an altered PI3K pathway, and focally in close association with genetically altered myoepithelial cells at the site of tumor initiation. The exact trajectory behind this bi-lineage phenomenon remains poorly understood.Methods and resultsHere we used a breast cancer relevant transduction protocol including hTERT, shp16, shp53, and PIK3CAH1047R to immortalize FACS isolated luminal cells, and we identified a candidate multipotent progenitor. Specifically, we identified a keratin 23 (K23)+/ALDH1A3+/CALML5− ductal-like progenitor with the potential to differentiate into CALML5+ lobular-like cells. We found that the apparent luminal phenotype of these oncogene transduced progenitors was metastable giving rise to basal-like cells dependent on culture conditions. In 3D organoid culture and upon transplantation to mice the bipotent progenitor cell line organized into a bi-layered acinus-like structure reminiscent of that of the normal breast gland.ConclusionsThese findings provide proof of principle that progenitors within the human breast luminal epithelial compartment may serve as a source of correctly positioned myoepithelial cells. This may prove useful in assessing the role of myoepithelial cells in breast tumor progression.

Current status of biological control of introduced Phragmites in Canada: Insights from initial years of post-release monitoring and a larval density release experiment.

Introduced Phragmites (Phragmites australis australis (Cav.) Trin. Ex Steud.) is one of the most invasive plants in North America. To supplement existing management tools, a classical biological control program began in Canada in 2019 using two host-specific stem-boring moths, Archanara neurica (Hübner) and Lenisa geminipuncta (Haworth) (Lepidoptera: Noctuidae). In this article, we summarize the first three years of monitoring data for L. geminipuncta and A. neurica as biological control agents for introduced Phragmites. First, we assess agent presence and activity in the initial years post-release based on feeding damage from long-term monitoring data across 30 release sites initiated between 2019 and 2023. Second, we investigate the within-site distribution of agent feeding damage to improve future monitoring and agent collection from nurse sites. Third, we report the results of an experiment to determine optimal release densities of A. neurica larvae. We found agent feeding damage at 92% of initial release sites in the first year and agent activity persisted at all of these sites into years two and three post-release. Patterns of agent feeding damage suggest that the agents disperse quickly through the patch following release, favouring the interior area over the edges of introduced Phragmites stands. Finally, releasing intermediate densities of 40 A. neurica larvae per release point was more efficient than releasing either units of 20 or 80 larvae. The results of the first three years of monitoring are highly encouraging for the introduced Phragmites biological control program. Insights from these early monitoring results will be used to refine optimal release strategies, improve our ability to locate egg-bearing stems at nurse sites to facilitate the collection and redistribution of agents to new release locations, and inform protocols for longer-term monitoring of impacts on the target weed once agents are established.

The impact of radiation therapy on thyroid function in patient with head and neck tumors

Background. Head and neck cancers (HNC) accounted for 1,518,133 new cases and 510,771 new deaths worldwide. The first reports of hypothyroidism following radiotherapy (RT) for HNC were published in the 1960s. The objective of this study was to ascertain the frequency of thyroiditis in patients with HNC and to establish the threshold of radiation dose volume for radiation-induced hypothyroidism in HNC. Methods. This was a prospective study of 35 patients with HNC treated with IMRT-VMAT. The following characteristics were examined: age, gender, comorbidity, initial tumor site, histology, surgical margin resection, radiation therapy dosage, V40, V50, V60 (percentage of thyroid tissue volume), 95% dose received, mean dose, minimum dose, and maximum dose. Thyroid assessment was performed using ultrasonography of the neck. Thyroid function was determined by TFT tests (TSH, free T3, and free T4), which were done at baseline before treatment and after RT for each case. Results. In this study, the mean age was 57.71 ± 11.43 years, with males comprising 68.6% (24 patients) and females comprising 31.4% (11 patients). Regarding TSH, the results showed that post-RT, the mean level of TSH was significantly higher than pretreatment, with a significant difference (P = 0.009). Regarding fT3, the results showed that post-RT, the mean level of fT3 was significantly lower than pretreatment, with a significant difference (P = 0.007). Regarding fT4, the results showed that post-RT, the mean level of fT4 was significantly lower than pretreatment, with a significant difference (P = 0.015). In addition, the mean 95% dose was 6.8 Gy (median = 4 Gy). The percentages of thyroid tissue volumes at V40, V50, and V60 were 79.47%, 39.28%, and 38.02%, respectively. The incidence of hypothyroidism was 14.3%, and the euthyroid incidence rate was 85.7%. Conclusions. There is a strong correlation between radiation therapy doses exceeding 66 Gy and the occurrence of hypothyroidism. The levels of fT3 and fT4 decreased after RT, while TSH levels increased. In dosimetry, the mean 95% dose was 6.8 Gy. The percentages of thyroid tissue volumes at V40, V50, and V60 were 79.47%, 39.28%, and 38.02%, respectively. The incidence of hypothyroidism was 14.3%, and the euthyroid incidence rate was 85.7%.

Application of forecast‐informed reservoir operations at US Army Corps of Engineers dams in California

AbstractThe US Army Corps of Engineers (USACE) prescribes flood control operations for reservoirs it regulates in watershed‐specific water control manuals (WCMs), which can be decades‐old and may not capture changed conditions in the watersheds or include the benefit of state‐of‐the‐science weather and streamflow prediction. Considering the specific characteristics of a reservoir, forecast‐informed reservoir operations (FIRO) may be used to enhance flood risk reduction, improve water availability, and achieve other benefits. The first FIRO pilot project at Lake Mendocino in California focused on determining if water supply reliability could be improved using FIRO without increasing flood risk. The final report concluded that FIRO concepts could indeed improve water supply reliability while enhancing flood risk reduction. Subsequently, USACE chose additional reservoir systems in California with different characteristics as additional pilot study locations to further investigate FIRO concepts. These successful FIRO efforts have provided justification to continue its expansion beyond the initial pilot sites. The lessons learned from the FIRO pilot projects are being used to inform the development of the FIRO Screening Process, a screening level framework intended to scale up the implementation of FIRO. The lessons learned could support FIRO implementation at suitable USACE reservoirs by updating WCMs.

Full-field quantitative visualization of shock-driven pore collapse and failure modes in PMMA

The dynamic collapse of pores under shock loading is thought to be directly related to hot spot generation and material failure, which is critical to the performance of porous energetic and structural materials. However, the shock compression response of porous materials at the local, individual pore scale is not well understood. This study examines, quantitatively, the collapse phenomenon of a single spherical void in PMMA at shock stresses ranging from 0.4 to 1.0 GPa. Using a newly developed internal digital image correlation technique in conjunction with plate impact experiments, full-field quantitative deformation measurements are conducted in the material surrounding the collapsing pore for the first time. The experimental results reveal two failure mode transitions as shock stress is increased: (i) the first in situ evidence of shear localization via adiabatic shear banding and (ii) dynamic fracture initiation at the pore surface. Numerical simulations using thermo-viscoplastic dynamic finite element analysis provide insights into the formation of adiabatic shear bands (ASBs) and stresses at which failure mode transitions occur. Further numerical and theoretical modeling indicates the dynamic fracture to occur along the weakened material inside an adiabatic shear band. Finally, analysis of the evolution of pore asymmetry and models for ASB spacing elucidate the mechanisms for the shear band initiation sites, and elastostatic theory explains the experimentally observed ASB and fracture paths based on the directions of maximum shear.

Implementation of biotechnological techniques for the propagation and introduction of Trichosanthes kirilowii Maxim

Trichosanthes kirilowii Maxim. is classified among the 50 most important medicinal plants used in traditional Asian medicine. This species is endemic and reproduction from seeds in the conditions of Central Europe is inefficient. The present study focused on the implementation of effective propagation of T. kirilowii, including standardisation of seed germination conditions, reproduction of the plant based on micropropagation, and introduction to field conditions. Four types of explants were tested on six types of media in various variants of culture conditions. Additionally, anatomical and histological analyses of specimens obtained through the in vitro cultivation were carried out, with particular emphasis on the site of initiation of aboveground and underground shoots. Microscopic analyses showed that the T. kirilowii shoots and roots obtained in the in vitro culture formed in the process of organogenesis via direct regeneration. Even though the callus did not participate in the regeneration of the entire plant, the micropropagation protocol proposed in the study was efficient: 6–8 shoots were obtained from 1 explant. The entire micropropagation process from the explant to an adult individual growing in the ground lasted 122 days. The protocol for T. kirilowii micropropagation in vitro cultures provides a fast, efficient, and robust approach to propagation of this species. The biotechnological applications in the reproduction of T. kirilowii will help not only to increase the number of daughter plants but also to multiply individuals of the appropriate sex, which will increase the probability of production of fruits in this dioecious species.

Twinning mediated cryogenic toughness in an additively manufactured high Mn steel by manipulating stacking fault energy

The insufficient cryogenic toughness of wire-arc additively manufacturing (WAAM) component hinders their application in cryogenic fields. We report that tungsten is effective in enhancing the impact toughness of WAAM components, increasing it from 42 to 106J at 77K. The outstanding cryogenic toughness depends on the interaction between dislocations and twins, where the thickness of twins plays a pivotal role in determining whether they hinder or facilitate dislocation movement. Twins below 6.1nm hinder dislocations, impeding deformation, while those exceeding 21.7nm coordinate with the matrix orientation, aiding dislocation movement and forming microbands. The W element reduces the critical twinning stress from 112.3 to 83.5MPa by manipulating the stacking fault energy and grain size, thereby altering the twinning structure. However, excessive W content forms large-sized precipitates, serving as crack initiation sites and reducing crack initiation energy.

Surface Roughness-Dependent Corrosion: Implications for Cochlear Implant Reliability

Abstract The corrosion behavior of platinum electrodes in cochlear implant (CI) systems is a critical factor affecting their long-term functionality. This study investigated the influence of the surface roughness of the platinum electrodes on their corrosion behavior. The results of in vitro experiments indicate that higher surface roughness tends to accelerate corrosion by providing numerous initiation sites. Although the electrochemical measurements of platinum electrodes with different surface roughnesses showed only slight differences in terms of shifts in potentials and higher corrosion current densities, data from the literature suggests an enhanced charge capacity with rougher surfaces. These findings contribute to an understanding of the failure mechanisms of CIs and can ultimately help to improve the design and durability of CI systems.

The effect of laser shock peening on the fatigue performance of 25Cr2Ni4MoV alloy

High-strength alloy steel, 25Cr2Ni4MoV, finds extensive application in the nuclear and petroleum industries. Experimental investigations and numerical simulations on the influence of laser shock peening on the fatigue characteristics of 25Cr2Ni4MoV alloy are conducted to examine the effect of this strengthening technique. The fatigue dangerous spots are all located at the excessive arc in the left side of the model, according to numerical fatigue simulations; With laser shock peening, the stress amplitude caused by the external load may be greatly reduced, increasing the fatigue life and improving the accuracy of the fatigue simulation model in predicting the potential fatigue fracture site. The fatigue test results indicate that after laser shock peening treatment, the number of fatigue cycles of the specimens was increased from 177,185 to 309,918, representing a significant improvement of 74.9 %. The laser shock peening can markedly enhance the fatigue resistance of 25Cr2Ni4MoV. The fatigue fracture morphology of the specimen exhibits multiple crack initiation sites. Following laser shock peening treatment, the mean distance between the fatigue striations in the fatigue propagation area is reduced. The striation spacing has decreased from 1.34 μm to 1.03 μm, resulting in a decrease of approximately 23.1 %, the rate of fatigue crack growth is reduced, and the area where the crack propagates is significantly increased.

Life history, population dynamics and impacts of cat predation on an endemic gadfly petrel in Cabo Verde

Insular fauna often suffers significant predation from invasive mammals, yet robust evidence of their impact from rigorous demographic analysis remains scarce. We aimed to understand the life history and population dynamics of the elusive Cape Verde petrel Pterodroma feae, an endemic seabird of the Cabo Verde archipelago, which is severely predated by cats. We analysed capture-mark-recapture data from birds mist-netted in a courtship area in 2007-2021 and monitored their nests between 2012 and 2021 on Fogo Island. Across all islands where this species breeds, we recorded cat predation rates and made additional captures of petrels in courtship areas. Demographic analysis revealed an 8.8% annual population decline of Cape Verde petrels, primarily driven by a 14.7% surplus mortality among breeders from threats in breeding areas, likely tied to the annual cat predation rate of at least 4% observed in monitored nests. Immature males exhibited lower survival rates, likely due to their increased vulnerability while seeking initial nest sites. The limited connectivity detected among and within islands, along with strong nest-site and mate fidelity rates, highlight the urgency of preventing local extinctions, which would be challenging to reverse. This study emphasizes the unsustainability of cat predation rates and the insufficiency of enhancing breeding success to counter the population decline, and it provides compelling evidence of a concerning decline of the Cape Verde petrel, primarily attributable to cat predation. Moreover, it emphasizes the significance of long-term demographic studies to understand the impact of invasive species on endangered populations.

Genome-wide quantification of polycistronic transcription in Leishmania major.

Leishmania major is a human-pathogenic, obligate parasite and the etiological agent of the most prevalent, cutaneous form of leishmaniasis, which is an important neglected, tropical disease with ~1.2 million new infections per year. Leishmania, and the whole order Trypanosomatida, are early eukaryotes with highly diverged gene expression and regulation pathways, setting them apart from their mammalian hosts and from most other eukaryotes. Using precision run-on sequence analysis, we performed a genome-wide mapping and density analysis of RNA polymerases in isolated nuclei of the protozoan parasite Leishmania major. We map transcription initiation sites at divergent strand switch regions and head-tail regions within the chromosomes and correlate them with known sites of chromatin modifications. We confirm continuous, polycistronic RNA synthesis in all RNA polymerase II-dependent gene arrays but find small varying RNA polymerase activities in polycistronic transcription units (PTUs), excluding gene-specific transcription regulation, but not PTU-specific variations. Lastly, we find evidence for transcriptional pausing of all three RNA polymerase classes, hinting at a possible mechanism of transcriptional regulation.IMPORTANCELeishmania spp. are pathogens of humans and animals and cause one of the most important neglected tropical diseases. Regulation of gene expression in Leishmania but also in the related Trypanosoma is radically different from all eukaryotic model organisms, dispensing with regulated, gene-specific transcription, and relying instead on highly regulated translation. Our work sheds light on the initiation, elongation, and termination of transcription, maps unidirectional, polycistronic transcription units, provides evidence for transcriptional pausing at or near starting points of RNA synthesis, and quantifies the varying transcription rates of the polycistronic transcription units. Our results will further the understanding of these important pathogens and should provide a valuable resource for researchers in the field of eukaryotic microbiology.

KAS-ATAC reveals the genome-wide single-stranded accessible chromatin landscape of the human genome.

Gene regulation in most eukaryotes involves two fundamental physical processes -- alterations in the packaging of the genome by nucleosomes, with active cis-regulatory elements (CREs) generally characterized by an open-chromatin configuration, and the activation of transcription. Mapping these physical properties and biochemical activities genome-wide -- through profiling chromatin accessibility and active transcription -- are key tools used to understand the logic and mechanisms of transcription and its regulation. However, the relationship between these two states has until now not been accessible to simultaneous measurement. To address this, we developed KAS-ATAC, a combination of the KAS-seq (Kethoxal-Assisted SsDNA sequencing and ATAC-seq (Assay for Transposase-Accessible Chromatin using sequencing) methods for mapping single-stranded DNA (and thus active transcription) and chromatin accessibility, respectively, enabling the genome-wide identification of DNA fragments that are simultaneously accessible and contain ssDNA. We use KAS-ATAC to evaluate levels of active transcription over different classes of regulatory elements in the human genome, to estimate the absolute levels of transcribed accessible DNA over CREs, to map the nucleosomal configurations associated with RNA polymerase activities, and to assess transcription factor association with transcribed DNA through transcription factor binding site (TFBS) footprinting. We observe lower levels of transcription over distal enhancers compared to promoters and distinct nucleosomal configurations around transcription initiation sites associated with active transcription. Most TFs associate equally with transcribed and nontranscribed DNA but a few factors specifically do not exhibit footprints over ssDNA-containing fragments. We anticipate KAS-ATAC to continue to derive useful insights into chromatin organization and transcriptional regulation in other contexts in the future.

Stereoselective Synthesis of 1,n-Dicarbonyl Compounds Through Palladium-Catalyzed Ring Opening/Isomerization of Densely Substituted Cyclopropanols.

We report a highly diastereoselective protocol for the synthesis of 1,4- and 1,5-dicarbonyl compounds from densely substituted cyclopropanols. The methodology involves a palladium-catalyzed ring opening reaction followed by a "metal-walk" and oxidation of a remote hydroxyl group. The methodology represents a new application of cyclopropanols as initiation sites for chain walking remote functionalization. Importantly, this approach provides a straightforward access to highly valuable succinaldehyde derivatives bearing vicinal quaternary and tertiary stereocenters as single diastereomers.

Steel Catenary Riser Fatigue Assessment: Fracture Mechanics Approach Versus S-N Curve Method.

In this paper, the fatigue resistance of a full-scale Steel Catenary Riser (SCR) girth weld is investigated using the Strength-Number of cycles (S-N) curve method based on weld formation quality and fracture mechanics approaches. The test results, presented in the form of S-N curves, are superior to the design curve E in BS 7608. Compared with the S-N curve determined by a resonant bending rig, the analytical fracture mechanics, i.e., engineering critical assessment (ECA) based on BS 7910, can provide a rational estimation of full-scale girth welds. For the numerical methods, the short crack growth phase is crucial to improving the accuracy and reliability of the assessment. For the girth weld with a concave root, the geometries of the weld cap are the predominant factors for fatigue life. Although the crack initiation site is always located at the outer surface regardless of the flushed or welded caps, the weld grinding treatment is still effective in promoting fatigue life.

A Time‐Saving Method for Evaluating the Fatigue Strength of Carburized High‐Alloy Steel Containing Carbides

To propose a time‐saving method for evaluating the fatigue strength of carburized steel, the fatigue behavior and fracture mechanism of carburized 14Cr14Co13Mo5 steels are studied by the rotary bending fatigue tests. It is found that the fatigue crack initiation site changes from surface to internal after carburizing due to the residual compressive stress and carbide cluster caused by the carburization. Besides, a notable correlation between the stress intensity of the cracked carbides at fatigue crack initiation site and fatigue life is observed in the carburized samples. This correlation allows for the estimation of fatigue strength at long conditional life based on samples tested at relatively high stress amplitudes with short lives, achieving a prediction error within 10% for the material studied. A significant time saving of ≈65% compared to the staircase method is achieved. The proposed method has significant implications for improving the efficiency fatigue strength evaluation in carburized steels containing carbides.

Stereoselective Synthesis of 1,n‐Dicarbonyl Compounds Through Palladium‐Catalyzed Ring Opening/Isomerization of Densely Substituted Cyclopropanols

We report a highly diastereoselective protocol for the synthesis of 1,4‐ and 1,5‐dicarbonyl compounds from densely substituted cyclopropanols. The methodology involves a palladium‐catalyzed ring opening reaction followed by a “metal‐walk” and oxidation of a remote hydroxyl group. The methodology represents a new application of cyclopropanols as initiation sites for chain walking remote functionalization. Importantly, this approach provides a straightforward access to highly valuable succinaldehyde derivatives bearing vicinal quaternary and tertiary stereocenters as single diastereomers.

Effects of Defects and Shot Peening on Fatigue Properties of Additively Manufactured CoCrFeNiTiMo-Based High-Entropy Alloys

Recently, the automotive industry has increasingly focused on additive manufacturing as a new technology for reducing the weights of automobiles. In this study, fatigue tests were conducted on additively manufactured high-entropy alloys with different defect characteristics to clarify the relationships between their defect characteristics and fatigue strengths and to elucidate their fatigue fracture mechanisms. In addition, the effect of shot peening as an effective fatigue strength improvement method for an additively manufactured component was investigated. As a result, when defects formed by additive manufacturing were smaller than crystal grains, the numbers and sizes of defects affect fatigue crack growth behavior and barely affect fatigue life. Shot peening reduces the crack growth rate and is effective in extending the fatigue life. However, improvement in the fatigue limit is not achieved because the crack initiation site is a facet. From the above results, for defects smaller than the grain size, shot peening is a more effective method for improving fatigue life than reducing the numbers and sizes of defects.

Heterogeneous folding landscapes and predetermined breaking points within a protein family.

The accurate prediction of protein structures with artificial intelligence has been a spectacular success. Yet, how proteins fold into their native structures inside the cell remains incompletely understood. Of particular interest is to rationalize how proteins interact with the protein homeostasis network, an organism specific set of protein folding and quality control enzymes. Failure of protein homeostasis leads to widespread misfolding and aggregation, and thus neurodegeneration. Here, I present a comparative analysis of the folding of 16 single-domain proteins from the same organism across a protein family, the Saccharomyces cerevisiae small GTPases. Using computational modeling to directly probe protein folding dynamics, this work shows how near identical structures from the same folding environment can exhibit heterogeneous folding landscapes. Remarkably, yeast small GTPases are found to unfold along different pathways either via the N- or C-terminus initiated by structure-encoded predetermined breaking points. Degrons as recognition signals for ubiquitin-dependent degradation were systematically absent from the initial unfolding sites, as if to protect from too rapid degradation upon spontaneous unfolding or before completion of the folding. The presented results highlight a direct coordination of folding pathway and protein homeostasis interaction signals across a protein family. A deeper understanding of the interdependence of proteins with their folding environment will help to rationalize and combat diseases linked to protein misfolding and dysregulation. More generally, this work underlines the importance of understanding protein folding in the cellular context, and highlights valuable constraints towards a systems-level understanding of protein homeostasis.

Building community through environmental regeneration: Operation Groundwork

Abstract In the 1970s, the Major Urban Fringe Experiment, later known as Operation Groundwork, emerged in response to industrial decline, growing awareness of industry’s environmental impact and grass-roots environmentalism and regeneration activism. Contrary to ideas of concomitant industrial and community decline, Groundwork demonstrates post-industrial regeneration’s community-building potential. Groundwork created bespoke volunteer groups, helped set up others and worked with already existing organizations. Unlike contemporary regeneration initiatives in the 1970s and 1980s, these community links were retained even as Groundwork expanded. This article traces Groundwork’s origins and its launch under Labour in the 1970s, its championing by Conservative Minister Michael Heseltine and its successful expansion from its initial test site in St Helens (Merseyside), to the North-West and then nationwide.

Fabrication of Ordered Nanohole Arrays by Anodization of Sn Substrates with Ordered Dimple Patterns Formed Using Porous Alumina Template

Abstract Sn thin films with ordered concave patterns were formed by the thermal deposition of Sn onto an anodic porous alumina template and peeling off the Sn thin film from the template. Ordered nanohole array structures with uniformly sized pores were obtained by anodizing the obtained Sn thin film. This is because each shallow concave formed on the Sn thin film acts as an initiation site for pore development during the initial anodization stage. On the basis of this process, large-area anodic Sn oxide films with ordered nanohole array structures were obtained using a large-area anodic porous alumina template. The interpore distance of the nanohole array structure in the anodic Sn oxide film can also be controlled by changing the structure of the anodic porous alumina template. The obtained anodic Sn oxide film with an ordered nanohole array structure is expected to be used for various applications, such as batteries, sensors, and solar cells.